Measles (Rubeola)

What measles is

Measles is caused by the measles virus, a paramyxovirus that only infects humans. It spreads in tiny droplets when an infected person breathes, coughs or sneezes, and it can stay in the air of a room for up to 2 hours after they leave. Its reproduction number of 12 to 18 means one case can infect a dozen or more susceptible people.

Measles was declared eliminated from the US in 2000 thanks to vaccination, but outbreaks keep occurring when travelers bring it into communities with low vaccine coverage. Worldwide it still kills over 100,000 people a year, mostly young children.

Measles symptoms and stages

1. Prodrome (days 1 to 4)

• Fever, often rising to 40 °C (104 °F) or higher
• A hacking cough
• Runny nose, described medically as coryza
• Red, watery eyes (conjunctivitis) and light sensitivity
• Tiredness and poor appetite

2. Koplik spots (days 2 to 3)

Tiny white or bluish-white spots, like grains of salt on a red background, appear inside the cheeks opposite the back teeth. They are specific to measles but fade as the rash comes out, so they are easy to miss.

3. Rash (days 3 to 5 of illness)

The measles rash:

• Begins as flat red spots at the hairline and behind the ears
• Spreads down the face, neck, trunk, arms and legs over about 3 days
• Has small raised bumps that merge into blotchy patches
• Is usually not very itchy
• Comes with the highest fever, when the person feels most unwell
• Fades in the same order it appeared, leaving brownish staining and fine peeling

4. Recovery

Fever breaks a day or two after the rash reaches the feet. The cough can last up to 2 weeks. Measles weakens the immune system for weeks to months afterward ("immune amnesia"), making other infections more likely.

What does measles look like compared with other rashes?

Measles complications

About 1 in 5 unvaccinated people in the US with measles is hospitalized. Complications are most common in children under 5, adults over 20, pregnant people, malnourished children and those with weak immune systems.

• Ear infection (otitis media): about 1 in 10 children, sometimes causing hearing loss
• Diarrhea and dehydration
• Pneumonia: the commonest cause of measles deaths in children
• Encephalitis: brain swelling in about 1 in 1,000 cases, which can cause deafness, intellectual disability or death
• Death: about 1 to 3 in 1,000 children in the US
• Subacute sclerosing panencephalitis (SSPE): a rare, fatal brain disease appearing 7 to 10 years after measles, more likely after infection in infancy
• In pregnancy: miscarriage, stillbirth, premature birth and low birth weight
• Blindness: where vitamin A deficiency is common

Diagnosis

Doctors suspect measles from the symptom pattern and exposure history. It is confirmed with:

• A throat or nose swab for measles RNA (PCR), the preferred test
• A urine sample for PCR
• A blood test for measles IgM antibodies

Measles is a reportable disease. Health departments trace contacts quickly to offer preventive vaccine.

Treatment

There is no specific antiviral treatment. Care focuses on comfort and preventing complications:

• Fluids and rest
• Fever relief: acetaminophen (paracetamol) or ibuprofen at the label dose. Never give aspirin to children or teenagers
• Vitamin A: recommended by the WHO and AAP for children with measles. It lowers the risk of severe illness and death. A doctor gives the dose
• Dim lighting for sore eyes, and cleaning crusted eyelids with cooled boiled water
• Antibiotics only for bacterial complications such as pneumonia or ear infections
• Isolation: stay home and away from others until 4 days after the rash began

How measles spreads and isolation

People with measles are contagious from 4 days before to 4 days after the rash appears. The virus spreads by air, so being in the same room, clinic waiting area or airplane cabin is enough. If you suspect measles, phone ahead before visiting a clinic or ER so staff can bring you in through a separate entrance.

Measles vaccine (MMR)

• Children: first dose at 12 to 15 months, second at 4 to 6 years
• Infants 6 to 11 months traveling internationally: an early dose, then the two routine doses
• Adults without evidence of immunity: at least one dose. Two doses for health care workers, college students and international travelers
• Effectiveness: one dose is about 93% effective, two doses about 97%
• Who should not get it: pregnant people and those with severely weakened immune systems, because it is a live vaccine
• Safety: side effects are usually mild (sore arm, fever, mild rash). Large studies have found no link between MMR and autism

Adults born before 1957 in the US are generally presumed immune, since nearly everyone caught measles then.

Frequently asked questions

What are the first signs of measles?

The first signs are a high fever, cough, runny nose and red, watery eyes, which appear 7 to 14 days after exposure. Two to three days later, tiny white Koplik spots may appear inside the cheeks. The typical rash follows 3 to 5 days after the fever starts.

How long is someone with measles contagious?

From 4 days before the rash appears until 4 days after. Because people spread it before they know they have measles, outbreaks move quickly. Anyone with measles should stay home and avoid contact with others, especially babies, pregnant people and anyone with a weak immune system.

Can you get measles if you are vaccinated?

It is uncommon. Two doses of MMR protect about 97% of people for life. A small number of vaccinated people can still catch measles in an outbreak, but their illness is usually milder and they are less likely to spread it.

Is measles dangerous for adults?

Yes. Adults are more likely than older children to develop pneumonia, hepatitis and encephalitis and to need hospital care. Pregnant people face risks of miscarriage and premature birth. Adults without proof of two MMR doses or past infection should talk to their doctor about vaccination.

What should I do if I was exposed to measles?

Check your vaccination records and call your doctor or health department. If you are not immune, an MMR dose within 72 hours of exposure, or immune globulin within 6 days for those who cannot have the vaccine, can prevent or soften illness. Watch for symptoms for 21 days.

Does measles rash itch?

The measles rash is usually only mildly itchy, unlike chickenpox. It starts on the face and behind the ears and spreads downward. The person typically feels most unwell, with the highest fever, when the rash appears. It fades after about 5 to 6 days, sometimes with fine peeling.